Well to try and answer my own curiosity looked into the whole Kindle font thing. I still can't get any clarity on what they are really doing, but this was rather insightful =>
https://sites.google.com/a/etccreati.../kdesignworks/. I would love the same analysis for the Kindle 3. It seems that the Kindle's default font is Cacecilla? It also appears that the Kindle 3 'does' render fonts with more weight (the author of the above review/analysis descripted the font as 'whispier' when rendered on a computer (LCD) monitor which I suspect is a truer representation of the font).
It was also interesting to note that the author found notable display differences in the screens across units due to production variances.